Prior Art
U.S. Pat. No. 5,133,323 issued to Christopher J. Treusch on Jul. 28, 1992 and assigned to a common assignee, teaches the location of a signal generating fuel pressure sensor mounted on a fuel rail. In that patent, the fuel pressure sensor housing has sensing and circuit means mounted on a platform therein to measure the difference between the manifold absolute pressure (MAP) supplied to one input of the housing and the fuel pressure in the fuel rail as determined by the variable pressure electric fuel pump supplied to another input of the housing. Electrical signals from the sensing and circuit means are supplied to control electronics for generating a signal to drive the electric fuel pump which is located in the fuel tank. The purpose of this system is to maintain the fuel pressure across the injectors at a predetermined value in relationship with MAP. With this predetermined value, the amount of fuel injected into the engine will be a function of the pulse width of the electrical signal generated by the electronic control unit in the fuel management system.
A disadvantage of this prior art system is that the for extreme fuel demand conditions such as full load, the pulse width of the fuel pulse to the injection approaches the maximum available time between injector actuations. Therefore, in order to have the proper amount of fuel available at wide open throttle, the size of the orifice in the injector valve must be of such size to allow the amount of fuel determined by the pulse width and fuel pressure to be sufficient to operate the engine during the maximum pulse width. The disadvantage of this is that at idle and other low power engine conditions, the orifice size requires that the pulse width be very short. Very short pulse widths may be in the non-linear region of the fuel injector operating range.